Tandem colloidal quantum dot solar cells employing a graded recombination layer
TL;DR: In this paper, a colloidal quantum-dot solar cell with two junctions, each designed to absorb and convert different spectral bands of light within the solar spectrum, is presented.
Abstract: Researchers report a colloidal quantum-dot solar cell that features two junctions, each designed to absorb and convert different spectral bands of light within the solar spectrum. The device offers a power conversion efficiency of 4.2% and an open circuit voltage of 1.06 V.
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TL;DR: The simple mesoscopic CH(3)NH( 3)PbI(3)/TiO(2) heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent J(sc)= 16.1 mA/cm(2), open-circuits photovvoltage V(oc) = 0.631 V, and a fill factor FF =0.57.
Abstract: We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH3NH3I and PbI2 in γ-butyrolactone on a 400 nm thick film of TiO2 (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH3NH3PbI3 as a back contact. Importantly, the CH3NH3PbI3 nanoparticles assume here simultaneously the roles of both light harvester and hole conductor, rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH3NH3PbI3/TiO2 heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent Jsc= 16.1 mA/cm2, open-circuit photovoltage Voc = 0.631 V, and a fill factor FF = 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m2 intensity. At a lower light intensity of 100W/m2, a PCE of 7.3% was m...
1,799 citations
TL;DR: In this paper, the authors demonstrate that PBDTT-DPP, a semiconducting polymer with a low bandgap of 1.44 eV, allows tandem polymer solar cells to reach power conversion efficiencies of around 8.6%.
Abstract: Researchers demonstrate that PBDTT-DPP, a semiconducting polymer with a low bandgap of 1.44 eV, allows tandem polymer solar cells to reach power conversion efficiencies of around 8.6%.
1,406 citations
Cites background from "Tandem colloidal quantum dot solar ..."
...5 eV) such as poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1b;3,4-b′] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), poly[(4, 4′ -bis(2-ethylhexyl)dithieno[3,2-b:2′,3′ -d]silole)-2,6-diylalt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSBTBT) and poly[3,6-bis(4′dodecyl-[2,2′]bithiophenyl-5-yl)-2,5-bis(2-ethylhexyl)-2,5-dihydropyrrolo[3,4-]pyrrole-1,4-dione] (pBBTDPP2) have either lowVOC, low JSC or low FF values, which are far from ideal for the tandem structure....
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TL;DR: This review will survey recent progress in the development of spectral converters, with a particular emphasis on lanthanide-based upconversion, quantum-cutting and down-shifting materials, for PV applications, and present technical challenges that arise in developing cost-effective high-performance solar cells based on these luminescent materials.
Abstract: Photovoltaic (PV) technologies for solar energy conversion represent promising routes to green and renewable energy generation. Despite relevant PV technologies being available for more than half a century, the production of solar energy remains costly, largely owing to low power conversion efficiencies of solar cells. The main difficulty in improving the efficiency of PV energy conversion lies in the spectral mismatch between the energy distribution of photons in the incident solar spectrum and the bandgap of a semiconductor material. In recent years, luminescent materials, which are capable of converting a broad spectrum of light into photons of a particular wavelength, have been synthesized and used to minimize the losses in the solar-cell-based energy conversion process. In this review, we will survey recent progress in the development of spectral converters, with a particular emphasis on lanthanide-based upconversion, quantum-cutting and down-shifting materials, for PV applications. In addition, we will also present technical challenges that arise in developing cost-effective high-performance solar cells based on these luminescent materials.
1,391 citations
TL;DR: The density of midgap trap states in CQD solids is quantified and shown to be limited by electron-hole recombination due to these states, and a robust hybrid passivation scheme is developed that can passivate trap sites that are inaccessible to much larger organic ligands.
Abstract: Improved performance in a photovoltaic device made of colloidal quantum dots is achieved through a combination of passivation by halide anions and organic crosslinking.
1,183 citations
TL;DR: This paper presents a meta-modelling system that automates the very labor-intensive and therefore time-heavy and expensive and therefore expensive and expensive process of designing and installing solar panels.
Abstract: Graham H. Carey,† Ahmed L. Abdelhady,‡ Zhijun Ning, Susanna M. Thon, Osman M. Bakr,‡ and Edward H. Sargent*,† †Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada ‡Division of Physical Sciences and Engineering, Solar & Photovoltaics Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia School of Physical Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China Department of Electrical and Computer Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
1,036 citations
References
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TL;DR: Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives.
Abstract: Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives. A transparent titanium oxide (TiO x ) layer separates and connects the front cell and the back cell. The TiO x layer serves as an electron transport and collecting layer for the first cell and as a stable foundation that enables the fabrication of the second cell to complete the tandem cell architecture. We use an inverted structure with the low band-gap polymer-fullerene composite as the charge-separating layer in the front cell and the high band-gap polymer composite as that in the back cell. Power-conversion efficiencies of more than 6% were achieved at illuminations of 200 milliwatts per square centimeter.
3,215 citations
TL;DR: In this paper, three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell, (ii) polymer−smiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell.
Abstract: The emergence of semiconductor nanocrystals as the building blocks of nanotechnology has opened up new ways to utilize them in next generation solar cells. This paper focuses on the recent developments in the utilization of semiconductor quantum dots for light energy conversion. Three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell (ii) polymer−semiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell. Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiency of the solar cell. Various strategies to maximize photoinduced charge separation and electron transfer processes for improving the overall efficiency of light energy conversion are discussed. Capture and transport of charge carriers within the semiconductor nanocrystal network to achieve efficient charge separation at the electrode surface remains a major challenge. Directing the future resear...
2,434 citations
TL;DR: Sittingizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers, and makes use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
Abstract: In contrast to traditional semiconductors, conjugated polymers provide ease of processing, low cost, physical flexibility and large area coverage1. These active optoelectronic materials produce and harvest light efficiently in the visible spectrum. The same functions are required in the infrared for telecommunications (1,300–1,600 nm), thermal imaging (1,500 nm and beyond), biological imaging (transparent tissue windows at 800 nm and 1,100 nm), thermal photovoltaics (>1,900 nm), and solar cells (800–2,000 nm). Photoconductive polymer devices have yet to demonstrate sensitivity beyond ∼800 nm (refs 2,3). Sensitizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers. Here we use such a nanocomposite approach in which PbS nanocrystals tuned by the quantum size effect sensitize the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) into the infrared. We achieve, in a solution-processed device and with sensitivity far beyond 800 nm, harvesting of infrared-photogenerated carriers and the demonstration of an infrared photovoltaic effect. We also make use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
1,860 citations
TL;DR: An ultrathin donor-acceptor solar cell composed entirely of inorganic nanocrystals spin-cast from solution is introduced, elucidates a class of photovoltaic devices with potential for stable, low-cost power generation.
Abstract: We introduce an ultrathin donor-acceptor solar cell composed entirely of inorganic nanocrystals spin-cast from solution. These devices are stable in air, and post-fabrication processing allows for power conversion efficiencies approaching 3% in initial tests. This demonstration elucidates a class of photovoltaic devices with potential for stable, low-cost power generation.
1,701 citations
TL;DR: The tailored selection of absorption onset energy through the quantum size effect, combined with deliberate engineering of the sequence of nanoparticle fusing and surface trap functionalization, underlie the superior performance achieved in this readily fabricated family of devices.
Abstract: Solution-processed electronic and optoelectronic devices offer low cost, large device area, physical flexibility and convenient materials integration compared to conventional epitaxially grown, lattice-matched, crystalline semiconductor devices. Although the electronic or optoelectronic performance of these solution-processed devices is typically inferior to that of those fabricated by conventional routes, this can be tolerated for some applications in view of the other benefits. Here we report the fabrication of solution-processed infrared photodetectors that are superior in their normalized detectivity (D*, the figure of merit for detector sensitivity) to the best epitaxially grown devices operating at room temperature. We produced the devices in a single solution-processing step, overcoating a prefabricated planar electrode array with an unpatterned layer of PbS colloidal quantum dot nanocrystals. The devices showed large photoconductive gains with responsivities greater than 10(3) A W(-1). The best devices exhibited a normalized detectivity D* of 1.8 x 10(13) jones (1 jones = 1 cm Hz(1/2) W(-1)) at 1.3 microm at room temperature: today's highest performance infrared photodetectors are photovoltaic devices made from epitaxially grown InGaAs that exhibit peak D* in the 10(12) jones range at room temperature, whereas the previous record for D* from a photoconductive detector lies at 10(11) jones. The tailored selection of absorption onset energy through the quantum size effect, combined with deliberate engineering of the sequence of nanoparticle fusing and surface trap functionalization, underlie the superior performance achieved in this readily fabricated family of devices.
1,680 citations